ipvs: Remove possibly unused variable from ip_vs_out

Eric's net namespace changes in 1b75097d leaves net unreferenced if
CONFIG_IP_VS_IPV6 is not enabled:

../net/netfilter/ipvs/ip_vs_core.c: In function ‘ip_vs_out’:
../net/netfilter/ipvs/ip_vs_core.c:1177:14: warning: unused variable ‘net’ [-Wunused-variable]

After the net refactoring there is only 1 user; push the reference to the
1 user. While the line length slightly exceeds 80 it seems to be the
best change.

Fixes: 1b75097d("ipvs: Pass ipvs into ip_vs_out")
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
[horms: updated subject]
Signed-off-by: Simon Horman <horms@verge.net.au>